A walking assist device which assists a walking motion by applying torque to a leg joint of a user has been researched. Patent document 1, for example, discloses a walking assist device which assists walking of a user having one leg that does not move freely. Hereinafter, in the present specification, a leg which the user can move freely is called a “sound leg” and a leg in which the user cannot freely move at least one joint is called an “affected leg”. Furthermore, in the present specification, the portion from the knee to the ankle is called “lower leg”. The walking assist device disclosed in Patent document 1 measures a pattern of motion of a sound leg with a sensor, and applies torque to a joint of an affected leg in such a manner that the pattern of motion of the affected leg follows the pattern of motion of the sound leg.
Patent document 1: Japanese Patent Application Publication No. 2006-314670